Script for multiple erlang applications multiple computers and some other questions

Question

I have two Erlang applications, for example, app1 and app2. I want to run them on three nodes when each node has its own config file.
Also, I need to run app1 before app2.
app1 must be running on every node. app2 is the same program for all nodes, but only one node runs it at the same time; the other nodes waits for the case of the current node will fail.

Example of running:

node 1:

erl -sname cp1 config cp1
application:start(app1).
application:start(app2).

node 2:

erl -sname cp2 config cp2
application:start(app1).
application:start(app2).

node 3:

erl -sname cp3 config cp3
application:start(app1).
application:start(app2).

All nodes need to start together because of the sync time (I set this parameter to 10000) in the config file and the same for app2.
To check that my program works as I want, I do this by myself, that's easy: I have control on the timing, I open a terminator with 3 terminals, do a copy-paste to commands and everything is ok.

My questions are:
I have 3 computers. I need one node for one computer. How to write a script for each computer that does it automatically?
Can I insert Erlang commands to bash script? What the best way to do this? How can I deal with the problem of sync? Can I set sync time to infinity?

cp1 code: (same for the others, just with changes in sync mandatory)

[{kernel,
  [{distributed, [{app2, 2000, [{cp1@dev1, cp2@dev1, cp3@dev1}]}
    ]},
   {sync_nodes_mandatory, [cp2@dev1, cp3@dev1]},
   {sync_nodes_timeout, 10000}
  ]
 }
].

app2.app code:

{application, app2,
 [{description, "An OTP application"},
  {vsn, "0.1.0"},
  {registered, []},
  {mod, {app2_app, []}},
  {applications,
   [kernel,
    stdlib,
    app1
   ]},
  {env,[]},
  {modules, []},

  {licenses, ["Apache 2.0"]},
  {links, []}
 ]}.

score 0 · Answer 1 · answered Jul 13 '20 at 08:22

I have 3 computers, I need 1 node for 1 computer. How to write a script for each computer that does it automatically?

I'd recommend using a tool to generate a release, such as rebar3, the release includes a boot script that starts the node with the config files.
I'd also recommend activating the -heart flag in your case, or install the release as a systemd service.

Can I insert erlang commands to bash script? What the best way to do this?

You can use escript to handle this, you can check this question for a example on how to do that (TL;DR: You can, but it starts a new node).

How can I deal with the problem of sync? Can I set sync time to infinity?

From distributed applications, yes, you can set the sync time to infinity.

Script for multiple erlang applications multiple computers and some other questions

1 Answers1